Life cycle assessment of food waste management options

Abstract

This environmental assessment of alternative means for managing food waste is based on the life cycle assessment (LCA) methodology. It covers the service provided by a household in-sink food waste processor (FWP) unit, and alternatives to it. The three alternatives considered are home composting, landfilling food waste with municipal waste (‘‘codisposal’’) and centralised composting of green (food and garden) waste. The functional unit is defined as management of the food waste produced by a Sydney household in one year. The environmental assessment includes eight environmental indicators and impact categories. This LCA study identifies an environmentally preferable option as well as the key environmental issues. If operated aerobically, home composting has the least environmental impact in all impact categories. The environmental performance of the codisposal option is relatively good, except with respect to climate change and eutrophication potential. The FWP performed well in terms of energy usage, climate change and acidification potentials, although it makes a large contribution to eutrophication and toxicity potentials. Demonstration of the relatively high water consumption of the FWP is an important outcome of this LCA study, as Australia is the driest inhabited continent on earth. Compared with the other three options, centralised composting has a relatively poor environmental performance due to the energy-intense waste collection activities it requires. Implementing a separate collection and transportation system for organic waste results in relatively high environmental impacts due to the frequency of collections and the small quantities of green waste collected per household. Compared with European cities, significantly larger distances have to be travelled in Sydney, differentiating this LCA from previous work. Non-recurrent impacts of the FWP are identified as causing large contributions to the overall result for this waste management option due to the types of materials used and the low operational capacities of the FWP. Finally, although home composting is clearly the best option in terms of the categories examined in this LCA, there is an important caveat to this result. If operated without due care, home composting loses its allure due to the high greenhouse gas emissions consequent to anaerobic methanogenesis. Although home composting has the capacity to be the best food waste management option, it can also perform worst in relation to a subject in which Australia is already at the bottom of its class.